The longer the battle goes, the better chances the gorilla has. The bear is stupid compared to a gorilla, but has probably triple both strength and length in comparison. Early on, the bear is in kill mode and the gorilla must avoid being crushed or mauled. But as the battle continues the dumb bear, not attaining victory despite what its natural instincts told it to do, would become confused and annoyed, giving the gorilla a chance to gain its back and hammer its grizzly haired skull in.